I think it's Washington that has a fan so obnoxious (lawyer naturally) that he was actually interviewed on Larry King. He deliberately gets season tickets behind the visitors bench just to yell profane and racailly charged insults all game, every game. I've read articles that there are similar 'people' in other cities, although I don't know about Detroit. I remember when Vernon Maxwell was suspended a few years ago the fan he attacked was ridiculing the death of Maxwell's daughter.
Ron Artest is an egomanical thug player, but then so is Ben Wallace. Both seemed to be already very angry over the pushing incident during the game.
Fault of the fans? I don't know about 99%, I come down more on 50/50 (pox on both houses). Jerks fighting jerks. I do think the NBA in particular needs to (1) beef up security as the fans are so much closer to the players and (2) deal with jerk fans who do nothing more than get drunk and yell obscene and racist remarks to players just because they think they can.
I don't think there is any excuse to go up into the stands, but the NBA can help matters greatly by cutting off the alcohol at halftime, increasing security and throwing out fans who want to cause trouble.